The present invention relates generally to gas turbine engines, and, more specifically, to low NO.sub.x combustors therefor.
A gas turbine engine includes a combustor having a plurality of fuel injectors typically cooperating with air swirlers which mix fuel and air to form a suitable fuel/air mixture which is ignited for generating hot combustion gases. The products of combustion include various undesirable emissions such as smoke or hydrocarbons, carbon monoxide, and nitrogen oxides (NO.sub.x) These emissions are dependent in part on the richness or leanness of the fuel/air mixture and are typically mutually exclusive increasing the difficulty of achieving a suitable combustor design.
Furthermore, in a gas turbine engine configured for powering an aircraft in flight, the engine and combustor operate over varying power levels and temperature and require corresponding design for achieving stable combustor operation. Many fuel injection points are provided around the circumference of the combustor which affects the circumferential and radial temperature distribution of the combustion gases discharged to a high pressure turbine which extracts energy therefrom. The circumferential temperature distribution is typically represented by a conventional pattern factor, and the radial temperature distribution is represented by a conventional profile factor.
Additional combustor design considerations include fuel thermal breakdown and coking of the fuel injectors due to the temperature environment of the fuel injector And, autoignition, flashback, and flammability are additional design considerations for obtaining a suitable combustor in a gas turbine engine.
It is desired to further reduce NO.sub.x emissions in a gas turbine engine combustor without adversely affecting performance of the combustor under these other operating parameters.